1. Field of the Invention
This invention relates to an air vent device for a fuel tank on a vehicle, such as an automobile, and more particularly to an air vent device for such a fuel tank, consisting of first and second air vent pipes connected to the portions of an upper section of a fuel tank which are spaced from each other in the lateral direction of the vehicle, and a main air vent pipe connected at its inner end to the first and second air vent pipes and which communicates at its outer end with the atmospheric air. Thus, even in the case where a surface of a fuel in a fuel tank is inclined to right or left with respect to the lateral axis thereof when the vehicle turns to apply a centrifugal force to the fuel or when the vehicle runs or parks on an inclined road surface, at least one of the first and second air vent pipes is not blocked from an upper space in the fuel tank so as to enable the fuel to be fed reliably from the fuel tank to an engine at all times.
2. Description of the Prior Art
In a conventional air vent device of this kind, a connecting point of first, second and main air vent pipes is positioned above two surfaces, which are inclined to right and left at a maximum angle with respect to the lateral axis of a fuel tank, of the fuel therein to keep at least one of the first and second air vent pipes communicated with an upper space in the fuel tank when the fuel surface is inclined. In such an air vent device, it is necessary that the connecting point mentioned above be set in a position which is spaced sufficiently in the upward direction from the fuel tank. This makes it necessary to reserve a space of a large height between a floor of a vehicle and the fuel tank for setting the fuel tank under the floor. Moreover, there is naturally a limit to a road clearance of the fuel tank. This results in a problem of the flattening of the fuel tank and also of a decrease in the capacity thereof.